The applicant is the proprietor of PCT/ES 2006/000203, which describes a method for extracting the contents from closed flexible containers through irrigation water; it also describes the device for putting said method into practice and the container used therein.
More specifically, this patent uses a tight container made of plastic material, containing fertilizer, which container is intended to be introduced into a container holder, which is in turn provided with a tight closure, based on a body and a lid, intended to be intercalated into a branch of the conduit for supplying the irrigation water, like a bypass, such that part of the water passes through the container holder, entering through its lid and exiting through its bottom, as a result of the fact that during the closing maneuver for closing same the lid and the bottom of the container break, such that as the water passes through the device the fertilizer gradually dissolves and is entrained by the water.
This basically acceptable system has in practice certain drawbacks, specifically the following:                The fertilizer is not metered as precisely as desired.        The pressure in the container holder is virtually the mains pressure, which is undesirable in certain cases, such as for example in the irrigation of large surface areas, with considerable water flow rates and high pressure levels.        The system lacks a method for evacuating the air contained in the lower part when the container holding the fertilizer is introduced and closed, and such air would accumulate, since its density is lower than that of water in the upper portion of the container holder, which can entail a risk since air is a compressible fluid and the device works under pressure.        The closure system of the containers holding the fertilizer is not the most suitable one, and the same occurs with the entrance of the water which, since it occurs through the lid of the container holder, considerably hinders the closing maneuver for closing same.        The system lacks a control of the amount of fertilizers available at all times, such that the container must be replaced according to the time it is expected to last, which is inaccurate and the intended constant feed of fertilizers is occasionally interrupted for longer or shorter time periods.        